结合纯种分离纯化和变性梯度凝胶电泳法(DGGE)分析了中国不同区域污水处理厂的曝气池中活性污泥的微生物群落结构及差异性。其中,可培养微生物经纯化后对16s r DNA片段进行PCR扩增并测序,在Blast中分析后构建系统发育树。分离培养得到的89种细菌大部分属于β-变形菌门(Bataproteobacteria)、γ-变形菌门(Gamaproteobacteria)和厚壁菌门(Firmicutes)。DGGE分析表明所有活性污泥样品中的菌种丰富度都很高,不同的样品中存在很多相同的条带,是属于所有活性污泥中共有的优势菌群,说明不同的活性污泥系统具有高度的生物相似性;每个地区的样品中也都含有自己的特异条带。并且同一地区活性污泥的相似性大于不同地区活性污泥的相似性,主要与各地区不同的自然经济环境和人们的生活习惯相关。
A series of MnCeOx catalysts supported on cordierite honeycomb (Cord) were prepared by a combustion synthesis method using Mn(NO3)2 , Ce(NO3 )2·6H2O and citric acid. The effect of the molar ratio of Mn/Ce, calcination time, the amount of citric acid and the effect of water vapor on the catalytic properties for the complete oxidation of benzene were investigated. These catalysts were characterized by X-ray diffraction (XRD), H 2 temperature-programmed reduction (H2 -TPR), O2 temperature programmed desorption (O2 -TPD) and scanning electron microscopy (SEM) techniques. The results indicated that the MnCeOx /Cord catalyst with Mn/Ce molar ratio of 1:1, calcining for 7h and M n+ /(citric acid) molar ratio of 6 exhibited the highest catalytic activity. When the concentration of benzene was 1500 ppm and the gaseous hourly space velocity was 20000h -1 , the conversion of toluene was 99.1% at the reaction temperature of 300 oC.
